1. Field of the Invention
The present invention relates to a differential limiter.
2. Description of the Related Art
Japanese Patent Application Laid-Open No. 2004-116594 (JP2004116594) discloses a differential limiter (referred to as “differential limiting device” in the abstract thereof). The above differential limiter includes: 1) a housing 1, 2) a left pressure ring 4 and a right pressure ring 5 which are connected to the housing 1 in such a manner as to move axially, 3) a differential mechanism having a pair of a left side gear 6 and a right side gear 7 which mesh with a pinion gear 3 supported to a pinion shaft 2, 4) a cam mechanism using a pair of a cam 4A and a cam 5A which are formed, respectively, i) between the left pressure ring 4 and the pinion shaft 2 and ii) between the right pressure ring 5 and the pinion shaft 2, and 5) a pair of a left clutch 8 and a right clutch 9 (frictional clutches) which are disposed, respectively, i) between the left side gear 6 and a cylindrical part of the housing 1 and ii) between the right side gear 7 and the cylindrical part of the housing 1. The cam mechanism operates according to a torque inputted from the housing 1 to both of the left pressure ring 4 and the right pressure ring 5 via the cam mechanism, then pressing and thereby clutching each of the left clutch 8 and the right clutch 9, thus bringing about a differential limiting torque. In general, the above differential limiter has a torque sensitive structure, bringing about a differential limiting function featuring a good response according to the torque (driving torque) inputted to the housing 1.
In the differential limiter according to the JP2004116594, however, an inner space of the housing 1 is widely occupied by the differential mechanism from a shaft core side to a radial outer side, thereby a space for the cam mechanism is limited to between an outer periphery of the differential mechanism and an inner periphery of the housing 1 (cylindrical part).
In addition, for avoiding the differential mechanism, the each of the left pressure ring 4 and the right pressure ring 5 has a periphery thereof by making a detour in an axial direction. Thereby, a thrust force and an opposite thrust force which are caused to the cam mechanism clutch the left clutch 8 and the right clutch 9 (frictional clutches) via, respectively, the left pressure ring 4 and the right pressure ring 5, to be inputted to both side wall plates of the housing 1.
As described above, the differential limiter according to the JP2004116594 has a complicated structure and is therefore likely to be large in size. In addition, the housing 1 having the side wall plates to which the thrust force and the opposite thrust force of the cam mechanism are inputted needs to increase strength according to the thus applied thrust force and opposite thrust force, thereby likely to be heavy.